Ethereum Development Skill Skill

Ethereum Development Skill

Master Ethereum development including EVM internals, gas optimization, transaction mechanics, and client interactions.

Quick Start

# Invoke this skill for Ethereum development
Skill("ethereum-development", topic="gas", network="mainnet")

Topics Covered

1. EVM (Ethereum Virtual Machine)

Understand the execution environment:

Stack Machine: 256-bit words, 1024 depth
Memory: Linear byte array, expansion costs
Storage: Persistent key-value, 32-byte slots
Opcodes: Costs, effects, gas consumption

2. Gas Optimization

Reduce transaction costs:

Storage Packing: Fit multiple values in one slot
Calldata vs Memory: Choose efficiently
Loop Optimization: Cache storage reads
Custom Errors: Save gas on reverts

3. Transaction Mechanics

Master transaction lifecycle:

Types: Legacy (0), Access List (1), EIP-1559 (2)
Fee Estimation: Base fee, priority fee, max fee
Nonce Management: Sequential ordering
Receipts: Status, logs, gas used

4. Client Interactions

Work with Ethereum nodes:

RPC Methods: eth_, debug_, trace_
State Queries: Storage slots, code, balance
Event Subscriptions: Filter logs, topics

Code Examples

Gas-Efficient Storage

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.24;

contract Optimized {
    // Pack into single slot (32 bytes)
    struct User {
        uint128 balance;    // 16 bytes
        uint64 lastUpdate;  // 8 bytes
        uint32 nonce;       // 4 bytes
        bool active;        // 1 byte
        // 3 bytes padding
    }

    mapping(address => User) public users;
}

Read Storage Slot

import { createPublicClient, http, keccak256, encodePacked, pad } from 'viem';
import { mainnet } from 'viem/chains';

const client = createPublicClient({ chain: mainnet, transport: http() });

// Read mapping value: balances[address]
async function getBalance(contract: `0x${string}`, user: `0x${string}`) {
  const slot = keccak256(encodePacked(['address', 'uint256'], [user, 0n]));
  return await client.getStorageAt({ address: contract, slot });
}

EIP-1559 Transaction

import { createWalletClient, http, parseEther } from 'viem';

const client = createWalletClient({ transport: http() });

const hash = await client.sendTransaction({
  to: '0x...',
  value: parseEther('0.1'),
  type: 'eip1559',
  maxFeePerGas: parseGwei('30'),
  maxPriorityFeePerGas: parseGwei('2'),
});

Gas Optimization Cheatsheet

| Technique | Savings | Example | |-----------|---------|---------| | Storage packing | ~20k/slot | uint128 + uint128 in one slot | | Calldata vs memory | ~3/byte | Use calldata for read-only | | Unchecked math | ~80/op | unchecked { i++; } | | Custom errors | ~200+ | error Unauthorized() | | Short-circuit | Variable | Cheap checks first |

Common Pitfalls

| Pitfall | Issue | Solution | |---------|-------|----------| | Storage in loops | Expensive reads | Cache in memory first | | String storage | Uses multiple slots | Use bytes32 when possible | | Zero value storage | Full refund gone | Don't rely on SSTORE refunds |

Troubleshooting

"Transaction underpriced"

# Check current gas prices
cast gas-price --rpc-url $RPC
cast basefee --rpc-url $RPC

Set maxFeePerGas to at least 2x current base fee.

"Out of gas"

# Trace transaction to find issue
cast run --trace $TX_HASH --rpc-url $RPC

"Nonce too low"

# Get current nonce
cast nonce $ADDRESS --rpc-url $RPC

CLI Commands

# Foundry essentials
forge build --sizes          # Contract sizes
forge test --gas-report      # Gas consumption
forge snapshot               # Gas snapshots
cast storage $ADDR $SLOT     # Read storage
cast call $ADDR "fn()"       # Simulate call

Test Template

contract GasTest is Test {
    function test_GasOptimization() public {
        uint256 gasBefore = gasleft();
        target.optimizedFunction();
        uint256 gasUsed = gasBefore - gasleft();

        assertLt(gasUsed, 50000, "Too much gas used");
    }
}

Cross-References

Bonded Agent: 02-ethereum-development
Related Skills: solidity-development, web3-frontend

Version History

| Version | Date | Changes | |---------|------|---------| | 2.0.0 | 2025-01 | Production-grade with viem, gas optimization | | 1.0.0 | 2024-12 | Initial release |

Agent Skills: Ethereum Development Skill

Skill Files